Colorimeter flow cell



Get. 10, 197 s. ROSlN ETAL COLORIMETER FLOW CELL Original Filed May 5 United States Patent 3,345,910 CGLORIMETER FLOW CELL Seymour Rosin, Massapequa Park, and William J. Smythe,

Rye, N.Y., assignors to Technicon Corporation, a corporation of New York Continuation of application Ser. No. 192,149, May 3, 1962. This application Apr. 11, 1966, Ser. No. 549,091 1 Claim. (Cl. 8814) ABSTRACT OF THE DISCLOSURE A colorimetric analysis system for a gas segmentized sample stream includes a flow cell and a debubbler upstream of the cell for removing most of the gas from the stream. The cell is provided with an elongated relatively horizontal sight passageway portion; adjacent one end and opening into the bottom of the sight passageway, a lower inlet through which the debubb'led sample stream, including any residual gas, is positively inletted at a predetermined volumetric rate, and an upper outlet, diametrically over said inlet through which a portion of the inletted stream, including the residual gas, is positively removed; and adjacent the other end and opening into the bottom of the sight passageway, an upper outlet through which the remainder of the sample stream passes from the sight passageway.

This application is a continuation of U.S. Ser. No. 192,149, filed May 3, 1962, now abandoned.

This invention relates to flow cells for colorimeters.

One object of the invention is to provide aflow cell, especially useful for the colorimetric examination of minute volumes of liquid, with means for removing any residual air or gas which may be present in the liquid and which-Would otherwise interfere with the colorimetric examination thereof.

Another object of the invention is to provide an improved flow cell for colorimetrically examining liquid specimens of small volume and low concentration in respect to aningredient under investigation, wherein the flow cell is simply and inexpensively constructed and yet is efifective for the colorimetric examination of the liquid.

A further object is to providea flow cell which includes means which reduces or eliminates contamination of an incoming liquid by a preceding liquid.

The above and other objects, features and advantages of the invention will be more fully understood from the following description of the presently preferred embodiment of the invention considered in connection with the accompanying drawings which are to be considered as illustrative of the invention and not in limitation thereof.

In the drawings:

FIG. 1 is a more or less diagrammatic view of apparatus for the colorimetric treatment and examination of a liquid stream in accordance with the invention;

FIG. 2 is a vertical sectional view of a flow cell in accordance with the invention, on a greatly enlarged scale, and with light examining means diagrammatically illustrated in association therewith;

FIG. 3 is a vertical sectional view, on a smaller scale, taken on line 33 of FIG. 2;

FIG. 4 is a horizontal sectional view taken on line 44 of FIG. 2;

FIG/5 is a vertical sectional view, on a larger scale, of part'of the apparatus of FIG. 1;

FIG. 6 is a vertical sectional view of-a flow cell in accordance with another form of the invention; and

FIG. 7 is avertical end view of the flow cell of FIG. 6. Referring first to FIGS. 1 to 5 of the drawings in detail,

the flow cell 10 comprises a horizontal tubular member 12 of a suitable material, for example glass, preferably of the type sold under the trademark Pyrex. The opposite end walls 14 and 16 of the cell are light-permeable and a horizontal liquid passage 18, defined by the inner peripheral wall 13 of member 12, extends between said end walls, and serves as an elongated sight passageway portion for, the flow cell. A vertical tubular member 20 is adhesively secured to the bottom of member 12, adjacent end wall 16, and is in communication with passage 18 through opening 22 formed in the wall of member 12. A vertical tubular member 24, which is in vertical alignment with tubular member 20, is adhesively connected to the top of member 12, adjacent end wall 16, and is in communication with passage 18 through an opening 26 which is in diametrical vertical alignment with opening 22 and which is formed in member 12. Another vertical tubular member 28 is adhesively connected to the top of member 12, adjacent end wall 14, and is in communication with passage 18 through an opening 30 provided in member 12. The ends 32 of tubular members 20, 24 and '28 are tapered for receiving the ends of tubes for transmitting the fluid to and from passage 18 of the flow cell.

The inner peripheral wall 13 of member 12 is polished to allow light from beam 36 from light source 38 to enter wall 12 and be reflected at the outer surface of said wall into the liquid in passage 18. The light source includes suitable focusing lenses 40 and a filter 41, so that light beam 36 is focused in passage 18 near wall 14 and passes through the liquid in the passage to a photoelectric device 42 which operates a recorder 44 (FIG. 1) that records the light transmittance characteristics of the liquid as an indication of the quantity of a particular known constituent of the liquid under colorimetric examination. As subsequently indicated, with reference to FIG. 6, Wall 12 (FIG. 2) is as thin as practically possible so that as much as possible of the path of light is in the liquid and as little as possible is in said wall.

In the use of the apparatus for the colorimetric examination of a liquid, the liquid is pumped through a tube 46 having its outlet end connected to tubular member 20 so that the liquid flows vertically upwardly into passage 18 of the flow cell, through opening 22, and travels horizontally through the passage in a direction which is opposite to the direction of the passage of the light through the flow cell. The liquid flows from the passage, vertically upwardly, through outlet opening 30 into tubular member 28, and into an outlet tube 48 having its inlet end connected to the tubular member. The outlet end of tube 48 can be connected to waste or to some other receptacle, as

required or as desired.

A suction tube 50 is connected to tubular member 24 and is operable to aspirate any air or gas G which may be present in the incoming liquid so that the liquid, as it travels through passage 18 to outlet opening 30, is devoid of any air or gas which might otherwise interfere with the colorimetric examination of the liquid. A small quantity ofliquid is incidentally also removed concurrently with the removal of the gas G but the major portion of the liquid travels'through the passage and leaves the flow cell through outlet opening 30. The rate of flow of the fluids through member 24 should be high enough to insure the removal of all the residual gas with removal of a minimum quantity of the liquid. The rate of fiow of the incoming liquid through member 20 is such with respect to the flow rate of the liquid through tubular member 24 to insure that passage 18 is always filled with liquid.

Referring now to FIG. 1, there is shown a colorimetric analysis apparatus 52 of the type which is shown in U.S. Patent No. 2,797,149 issued June 25, 1957 and which utilizes the flow cell and associated apparatus of the present invention. The analysis apparatus includes a proportioning pump 54 and a separating device 56 for removing air segments from a liquid stream containing said segments. The sample liquid which is to be treated for colorimetric analysis is transmitted in the form of a stream through a pump tube 58 to a fitting 60 where it joins a stream of air or other inert gas and a stream of a color producing reagent transmitted through pump tubes 62 and 64, respectively. The fluids join each other in fitting 60 and form a segmented stream consisting of a series of liquid segments L (FIG. each containing a portion or the sample liquid and a portion of the color reagent, separated from each other by an intervening gas segment G. As indicated in the aforementioned US. Patent No. 2,797,149, the gas segments help cleanse the internal walls of the tubular passages of the apparatus. The constituents of each liquid segment are mixed together in a horizontal helical mixing coil 66 and are transmitted from the mixing coil through tube 67 to the separating device 56 which is operable to remove the gas segments from the stream and form a consolidated liquid stream which is transmitted to the flow cell for the colorimetric examination thereof.

As best seen in FIG. 5, the gas separating device 56 comprises a horizontal tubular passage 68 which is connected to a vertical passage 70 at a point intermediate the length thereof to form an upper arm 72 and a lower arm 74. The upper arm 72 provides a tubular olftake into which the gas segments G tend to rise and thereby escape from the segmented stream. To aid in this separation of the gas segments from the liquid segments, a suction tube 76, which is connected to aspirating pump tube 78, is also connected to tubular oiftake 72 so that the gas segments are aspirated from the liquid stream through said oiftake with a minor portion of the liquid, and the major portion of the liquid flows downwardly into arm 74 in the form of a consolidated stream which is transmitted to the flow cell through tube 46. As indicated above, if any gas remains in the liquid stream which is introduced into the flow cell, said gas rises in passage 18 of the flow cell, at the inlet end thereof, into member 24 and the removal of this remaining gas from the stream is aided by the aspirating action of tube 50 which is connected to the aspirating pump tube 80 of the pump.

The proportioning pump 54, which is schematically illustrated, may be of any suitable type though it is preferably of a type described in US. Patent No. 2,935,028 issued May 3, 1960. Briefly described, the pump comprises a plurality of resiliently flexible pump tubes which are compressed along their lengths for the pumping operation by the engagement therewith of a plurality of pressure rollers 82. The pressure rollers move longitudinally of the pump tubes to fully close said tubes progressively along their lengths against a platen 84 and thus propel the liquids or other fluids for transmitting them from sources of supply to points of delivery.

In actual practice, the wall of member 12 of the flow cell 10 is much thinner than shown, 'as illustrated by the flow cell 10' shown in FIGS. 6 and 7. The flow cell is made of the same material as cell 10 and comprises the relatively thin-walled horizontal part 12'. Light which pases into the wall of part 12' and is reflected at its outer surface back through the wall and into the liquid. By reason of the thin wall of part 12', most, if not substantially all, of the light which enters said wall from light source 38 is reflected to and passes through the liquid in said part. As shown, flow cell 10' includes tubular parts 24', 28' and inlet opening 22 which have the functions as parts 20, 24, 28 and inlet opening 22 of cell 10.

It is to be noted that opening 22' is considerably smaller in cross sectional area than the cross sectional area of the passage provided by member 20, about one-half the size, so that the incoming liquid speeds up as it passes through opening 22 which provides a scrubbing action on the adjacent surfaces of the cell. This results in the wiping of the surfaces by the incoming liquid thereby keeping said surfaces clean and preventing contamination of the incoming liquid by the preceding liquid due to the adherence of the latter of constitutents thereof on said surfaces.

A non-limiting but preferred example of the dimensions of flow cell 10' is as follows: passage 18', 15 mm. long; wall thickness, 0.5 mm; member 12, 3 mm. inside diameter; members 20, 24 and 28, 10 mm. long, 1 mm. inside diameter, and 0.5 mm. Wall thickness; and opening 26 is about one-half the cross sectional area of the passage of member 20. The inner diameter of passage 18' is about 3 mm., and its outer diameter is about 3.5 mm., the wall thickness being about 0.5 mm. Accordingly, for good results, the wall thickness should not exceed about 15% of the outer diameter of passage 18'.

It will be understood that the lengths of passages 18 and 18 will vary depending upon the liquid being analyzed and the concentration of the ingredient therein.

Preferably the flow cell is positioned so that member 12, in the case of cell 10, and member 12, in the case of cell 10, and member 12' in the case of cell 10', is in a horizontal position, but acceptable results can be obtained with said part of the flow cell in an inclined position, preferably not more than about 30 from its horizontal position.

Positioning of the cell with part 12 or 12' vertically is not recommended because such position interferes with the free upward flow of air bubbles into passages 24 or 24.

While I have shown and described the prefered embodiment of the invention, it will be understood that the invention may be embodied otherwise than as herein specifically illustrated or described, and that certain changes in the form and arrangement of parts and in the specific manner of practicing the invention may be made without departing from the underlying idea or principles of this invention within the scope of the appended clam.

What is claimed is:

An analysis system comprising a light source and a light detector having a beam of light therebetween whose path is more horizontal than vertical; a flow cell; said flow cell having an elongated sight passageway portion disposed in said light path with a light permeable subportion at each end thereof for the respective entrance and exit of said measuring beam of light, a first elongated portion opening into the bottom of said sight passageway portion immediately adjacent one of said ends thereof, a second elongated portion opening into the top of said sight passageway portion immediately adjacent said one of said ends thereof, and a third elongated portion opening into the top of said sight passageway portion immediately adjacent the other of said ends thereof; means for supplying liquid coupled to said first portion, for the entrance of a stream of liquid into said sight passageway portion at a predetermined volumetric rate; first means for withdrawing liquid coupled to said sec-0nd elongated portion, for the exit of a portion of the stream of liquid including any gas carried therein at a predetermined volumetric rate; second means for withdrawing liquid coupled to said third elongated portion, for the exit of the remaining portion of the stream of liquid after it has passed through the length of said sight passageway portion.

References Cited UNITED STATES PATENTS 1,471,342 10/1923 Logan 8814 2,405,479 8/ 1946 Whitlock 250218 3,046,831 7/ 1962 Isreeli 8814 3,109,714 11/1963 Skeggs 88-14 JEWELL H. PEDERSEN, Primary Examiner.

O. B. CHEW, Assistant Examiner. 

